FEL and Compton scattering applications at UCLA. .... (corresponding to the 9.6 and 10.6 jim beatwave combination), aw =10%, plasma wave width = 5OX.
Theory and Experiments on the Generation of Spontaneous Emission Using a Plasma Wave Undulator: A Progress Report R. L. Williams, C. E. Clayton, C. Joshi, T. Katsouleas and W. B. Mon University of California, Los Angeles Los Angeles, CA 90024 and
Jack Slater Spectra Technology, Inc. Bellevue, WA 98004
AB STRA CT We are studying the feasibility of using relativistically moving plasma waves as short wavelength undulators for possible
FEL and Compton scattering applications at UCLA. The remarkable property of such waves is that the wiggler parameter aw eA/mc2 can be on the order 0.1 while their wavelength w can be submillimeter. Such waves can be excited by either an intense electron bunch going through a plasma (plasma wake field) or a short but intense laser pulse going through the plasma (laser wake field).
A variation of the laser wake field scheme is the plasma beat wave excitation. Here a moderately intense laser pulse containing two frequencies excites the plasma wave resonantly. Using a laser pulse containing 10.27 im and 9.6 im lines of the CO laser that is approximately 400 ps (FWHM) and 200 OW of power, we were able to measure aw times the length product of 0.013 cm in our experiments. If a length of 0.75 cm is assumed, this implies an aw of 0.17 for a 7w 156 rim. Injection of an electron beam across such a plasma wave proved not to be feasible in these experiments, because the 0-pinch plasma source contained significant trapped magnetic fields. We are currently developing a field free plasma source which will permit transverse electron injection.
On the theoretical front, the electron trajectories in a relativistic plasma wave undulator have been simulated using a 3D model which includes emittance effects. We calculate the resulting radiation pattern produced by the electrons. We also analyze the scattered electron energies and spatial distributions, which may be useful as diagnostics in an experiment.
1. INTRODUCTION This paper presents a progress report on the theoretical and experimental work being done at UCLA and at Spectra Technology Inc. on the generation of spontaneous emission using relativistic plasma waves as undulators/wigglers. The words undulator and wiggler will be used interchangeably since the normalized strength of the field is 0.1
